function [ dx ] = oppodyna( t,x )

global miu rm n;

rx=x(1);
ry=x(2);
rz=x(3);
vx=x(4);
vy=x(5);
vz=x(6);

r=sqrt((rm+rx)^2+ry^2+rz^2);

drx=vx;
dry=vy;
drz=vz;
% dvx=2*n*vy-3*n^2*rx;
% dvy=-2*n*vx;
% dvz=-n^2*rz;
dvx=2*n*vy+n^2*rx-miu*(rm+rx)/r^3+miu/rm^2;
dvy=-2*n*vx+n^2*ry-miu*ry/r^3;
dvz=-miu*rz/r^3;

dx=[drx;dry;drz;dvx;dvy;dvz];

end

